JP2001016995A - Agricultural polyolefin-based resin multi-layered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an agricultural polyolefin-based resin multi-layered film excellent in transparency and heat-insulating property. SOLUTION: This agricultural polyolefin-based multiple layered film is obtained by using a polyolefin-based resin composition layer containing 8-20 wt.% blended material having (30/70)-(70/30) blending weight ratio of lithium aluminum magnesium and/or zinc complex hydroxide-condensed silicate salt to a hydrotalcite as an intermediate layer, and having a polyolefin-based resin composition-covering layers on its both sides, and is characterized by containing 5-15 wt.% blended material in the multiple-layered film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural film. More specifically, the present invention relates to an agricultural polyolefin resin multilayer film excellent in heat retention and transparency required for an agricultural polyolefin film.

[0002]

2. Description of the Related Art In recent years, in order to increase marketability and productivity of agricultural crops by semi-forcing or suppressing cultivation, agricultural vinyl chloride films, polyethylene, ethylene-vinyl acetate copolymers, and polyolefin resins have been used. BACKGROUND ART So-called house cultivation and tunnel cultivation, in which useful plants are cultivated under coating with agricultural covering materials such as films, are mainly performed. Above all, films composed mainly of polyolefin resins have stable chemical structures, so their mechanical properties hardly change even after long-term use, and they generate little toxic gas even when incinerated. Due to its low cost, it is becoming popular.

[0003]

However, a film mainly composed of a polyolefin resin is inferior in heat insulation and transparency as compared with a vinyl chloride film for agricultural use, and an improvement has been demanded. For example, with regard to heat retention, the temperature in a house or tunnel that has been heated by daylight irradiation during the daytime is easily cooled to a low temperature at night, especially at night on a sunny day, which has a significant adverse effect on the growth of crops. . Therefore, heat retention in agricultural films is a very important property.

[0004] By the way, this kind of cooling in an agricultural house or a tunnel is mainly caused by the fact that infrared rays radiated from an object having a temperature near normal temperature such as the ground penetrate through a film and dissipate outside, and such cooling is performed. To prevent
It is only necessary to block the transmission of infrared light, which is already known. The infrared energy distribution radiated from the ground or the like is similar to the infrared energy distribution radiated from a black body having the same temperature, and is approximately represented by a blank black body radiation formula.

Conventionally, the addition of a substance that absorbs and reflects infrared rays to agricultural films prevents the transmission and dissipation of infrared rays to improve the heat retention of the film, and absorbs infrared rays used for such purposes. Reflective substances include silicic anhydride, zeolite, hydrotalcite, etc., but the heat insulation is not sufficient, and the heat insulation is contained in a large amount in the film to make it close to the heat insulation of vinyl chloride film. However, there is a problem that transparency is hindered. The present invention overcomes the disadvantages of the conventional agricultural olefin film and provides an agricultural polyolefin resin multilayer film particularly excellent in heat retention and transparency.

[0006]

That is, the gist of the present invention is that the compounding weight ratio of the lithium / aluminum / magnesium and / or zinc composite hydroxide salt and the hydrotalcite compound is 30 / 70-70. An agricultural multi-layer film comprising a polyolefin-based resin composition layer containing 8 to 20% by weight of a composition in the range of 30/30 as an intermediate layer, and a polyolefin-based resin composition coating layer on both surfaces thereof. It is intended to provide an agricultural polyolefin-based resin multilayer film characterized in that the composition contains 5 to 15% by weight of a compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the lithium-aluminum-magnesium and / or zinc composite hydroxide condensed silicate used as the mixed component of the present invention, International Publication No. WO97 / 00828
The following general formula described in the gazette

[0008]

[Al ₂ (Li _1−X M _X ) (OH) ₆ ] _n (Si _y O _{2y + 1} ² ) _{1 + x} · mH ₂ O (1)

Wherein M is magnesium and / or zinc, x is a number in the range of 0.01 to 0.99, and m is 0 or a positive number. It expresses with. Compound (1) has an average secondary particle diameter of 5 μm
Or less, preferably 3 μm or less, more preferably 1 μm or less. The BET specific surface area is 50 m ² / g or less, more preferably 20 m ² / g or less. As the hydrotalcite compound used as the other mixed component of the present invention, the following general formula

[0010]

## EQU2 ## M 2 ⁺ _{1 -x} Al _x (OH) ₂ (A ^n- ) _{x / n} · mH ₂ O (2)

[0011] In the formula, M ²⁺ is a divalent metal ion of Mg, Ca or Zn, A ^{n-is Cl -, Br -, I -} ,
_{^{NO 3 2-, ClO 4-, SO}} 4 2-, CO 3 2-, Si
An anion such as O ₃ ²⁻ , HPO ₄ ²⁻ , HBO ₃ ²⁻ , and PO ₄ ²⁻ ; x is a numerical value satisfying the condition of 0 <x <0.5, and m is 0 ≦ m ≦ 2 which satisfies the condition of ≦ 2] (hereinafter referred to as “compound (2)”). For example, natural hydrotalcite, synthetic hydrotalcite and the like can be mentioned. Such a compound (2) can be used alone or in combination of two or more.

The average secondary particle size of the compound (2) is 10 μm.
m or less, particularly preferably 5 μm or less. When the average secondary particle size of the compound (2) is within the above range, a multilayer film having good transparency can be obtained. The compound (1) and the compound (2) have a compounding weight ratio of 30 / 70-
It is preferable to mix in a range of 70/30, more preferably in a range of 40/60 to 60/40. If it is outside this range, a sufficient mixing effect cannot be exhibited in terms of heat retention.

The amount of the mixture of the compound (1) and the compound (2) is 8 to 2 with respect to the polyolefin resin of the intermediate layer.
It is preferable to add the compound in an amount of 0% by weight, more preferably 10 to 15% by weight. If the amount is too small, the heat retaining property is insufficient, and if it is too large, the transparency is undesirably reduced. The compounding amount of the mixture of the compound (1) and the compound (2) is 5 to 15% by weight based on the whole multilayer film;
More preferably, the content is 5 to 10% by weight.

The polyolefin resin used in the intermediate layer of the present invention includes a homopolymer of α-olefin, for example, a copolymer of two or more α-olefins such as polyethylene and polypropylene, for example, ethylene / propylene copolymer. Polymers and ethylene / butene copolymers and other unsaturated monomers such as ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid copolymer, ethylene / (meth) acrylate copolymer Polymers and the like can be mentioned. Among these resins, density 0.93g
/ Cm ³ or less, a density of 0.93 g obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms in the presence of a metallocene-based olefin polymerization catalyst.
/ Cm ³ or less ethylene / α-olefin copolymer, ethylene acetate / vinyl acetate copolymer having a vinyl acetate content of 10% by weight or more are preferred in terms of transparency and heat retention, and particularly, the metallocene olefins described above. In the presence of a polymerization catalyst, an ethylene / α-olefin copolymer having a density of 0.93 g / cm ³ or less, which is obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms, in terms of transparency. Are better. This ethylene / α-olefin copolymer may be mixed with a high-pressure branched polyethylene produced with a radical catalyst as long as transparency is not impaired from the viewpoint of maintaining molding stability.

In the intermediate layer of the present invention, in addition to an anti-fogging agent, if necessary, a weather resistance stabilizer, as long as the object of the present invention is not impaired.
An antioxidant and the like can be added. As the anti-fogging agent, a general anti-fogging agent which is usually compounded in an agricultural film can be used. Specifically, for example, lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, polyethylene glycol monopalmitate, polyethylene glycol monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate , Glycerin monolaurate, glycerin monopalmitate, glycerin monostearate, glycerin monooleate, pentaerythritol monolaurate, sorbitan monopalmitate, sorbitan monobehenate,
Sorbitan distearate, diglycerin monooleate, triglycerindiolate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate,
Sodium butylnaphthalenesulfonate, acetyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, dodecylamine hydrochloride,
Lauryl lauramide ethyl phosphate, triethylacetylammonium iodide, oleylaminodiethylamine hydrochloride, basic pyridinium salt of dodecylpyridinium sulfate and the like. Among them, preferred are non-ionic fatty acids having 14 to 22 carbon atoms and esters of polyhydric alcohols such as sorbitan, sorbitol, glycerin, polyglycerin and propylene glycol or alkylene oxide adducts thereof. Surfactants and the like. These surfactants can be used alone or in combination of two or more.

The compounding amount of the antifogging agent is preferably 0.1 to 5 parts by weight, particularly preferably 0.3 to 3 parts by weight, per 100 parts by weight of the polyolefin resin. If the amount is less than 0.1 part by weight, sufficient anti-fogging property cannot be obtained, and if it exceeds 5 parts by weight, a large amount of blowout to the film surface is caused and transparency is impaired, which is not preferable.

The resin constituting the intermediate layer and the coating layer is as follows:
From the viewpoint of maintaining weather resistance and heat resistance, it is preferable to add a weather stabilizer, an antioxidant, and the like. The weather stabilizer is roughly classified into a light stabilizer and an ultraviolet absorber. As the light stabilizer, for example, a hindered amine light stabilizer is preferably used. As the ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, and a salicylic acid-based ultraviolet absorber are preferably used.

The amount of the weathering stabilizer is selected in the range of 0.05 to 3 parts by weight, preferably 0.1 to 0.5 part by weight, per 100 parts by weight of the polyolefin resin. Examples of the antioxidant include hindered phenol compounds such as 2,6-dialkylphenol derivatives and 2-alkylphenol derivatives, sulfur compounds having a thiol bond or a thioether bond containing a divalent sulfur atom, and trivalent phosphorus atoms. And the like. The amount of the antioxidant is selected in the range of 0.01 to 1 part by weight, preferably 0.02 to 0.5 part by weight, per 100 parts by weight of the polyolefin resin.

The polyolefin resin used in the coating layer of the present invention includes the polyolefin resin used in the intermediate layer. The composition of both surfaces to be coated is not limited to the same. The coating layer of the present invention may contain additives such as an antifogging agent, a weathering stabilizer and an antioxidant, as well as an antiblocking agent and an antifog agent, as long as the purpose is not impaired. .

As the anti-blocking agent, silica,
Talc, calcium carbonate, magnesium hydroxide, calcium sulfate, mica and the like are used. These antiblocking agents may be used alone or in combination of two or more. The compounding amount is selected within a range of 5 parts by weight or less, preferably 2 parts by weight or less per 100 parts by weight of the polyolefin resin.

Examples of the antifog include fluorine compounds having a perfluoroalkyl group and an ω-hydrofluoroalkyl group, and silicon compounds having an alkylsiloxane group. The amount of these antifog agents is 0.00.0 parts by weight per 100 parts by weight of the polyolefin resin.
It can be used in the range of 2 to 1.0 part by weight, preferably 0.04 to 0.3 part by weight. The amount of the antifog is 0.02 to 2 per 100 parts by weight of the polyolefin resin.
Parts by weight, preferably in the range of 0.01 to 1 part by weight.

The thickness of the coating layer of the multilayer film of the present invention is preferably 5 to 50 μm. When the thickness of the coating layer is less than 5 μm, the strength is substantially insufficient, so that it is not suitable as a film. The coating layer surface of the agricultural polyolefin resin multilayer film of the present invention, depending on the purpose of use, transparent, semi-pear,
It can take the form of satin.

The agricultural polyolefin resin multilayer film of the present invention is prepared by weighing the required amount of the polyolefin resin used in each layer and each additive, and using a ribbon blender, a Banbury mixer, a super mixer and other compounding machines and mixers. Mix. Next, the obtained composition can be prepared by coating (laminating) the outer layer, the intermediate layer, and the inner layer by a method known per se, for example, a method such as a coextrusion inflation method or a coextrusion T-die method.

The thickness of all the layers is preferably in the range of 40 to 200 μm in consideration of strength, performance, production cost and the like.
The thickness of the coating layer is preferably 5 to 50 μm. If the thickness of the coating layer is less than 5 μm, the strength is substantially insufficient, and thus the film is not suitable. The thickness of each layer is such that the intermediate layer is thicker than the coating layer, preferably 2 to 4 times the coating layer.

[0025]

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
It is not limited to the following example. In addition, the performance of the agricultural multilayer film was evaluated as follows.

(1) Transparency The parallel light transmittance of each film at a wavelength of 555 mm was measured by a spectrophotometer, and the value was shown.

(2) Thermal insulation Black body radiation energy-transmittance The black body radiation energy-transmittance was measured using a black body radiation energy spectrum at 15 ° C. as incident energy, and using an infrared spectrometer separately. The transmission energy spectrum obtained by multiplying the transmission spectrum of the film measured in the wavelength range of 4 μm to 25 μm was integrated to obtain the transmission energy, which was divided by the incident energy to obtain the transmittance. The smaller the transmittance, the better the heat retention.

Temperature difference inside and outside the house In a field in Isshi-gun, Mie Prefecture, a height of 1 m, a frontage of 2 m, and a depth of 2
m on each pipe house, and 15
The temperature difference between the inside and outside of the house having a height of cm was measured every hour from 18:00 to 7:00 the next morning, and the average value was calculated. Measurement is H1
The training was conducted from February 16 to February 17 of the year. The larger the temperature difference, the better the heat retention.

(Example 1) Lithium / aluminum / magnesium composite hydroxide condensed silicic acid shown in Table 1 with respect to an ethylene / vinyl acetate copolymer (vinyl acetate content: 15% by weight, melt index: 2 g / 10 min) 5% by weight of salt, 5% by weight of hydrotalcite, 1.5% by weight of sorbitan palmitate as an antifogging agent, 0.2% by weight of Chimassorb 944 (a hindered amine light stabilizer manufactured by Ciba Specialty Chemicals) as a weathering agent And UV53
1 (Sytec benzophenone UV absorber)
0.1% by weight, Irganox 101 as antioxidant
0 (Ciba Specialty Chemicals Co., Ltd., phenolic antioxidant) 0.1% by weight was blended and granulated to obtain a composition pellet (A).

Separately, an ethylene / vinyl acetate copolymer (vinyl acetate content 5% by weight, melt index 2 g / 1
0 minutes) and sorbitan palmitate 1 as an antifogging agent
% By weight, 1% by weight of diglycerin distearate, 0.2% by weight of Chimassorb 944 (a hindered amine light stabilizer manufactured by Ciba Specialty Chemicals) as a weathering agent, and UV531 (a benzophenone-based ultraviolet absorber manufactured by Scitech) 0 0.1% by weight, 0.1% by weight of Irganox 1010 (phenolic antioxidant, manufactured by Ciba Specialty Chemicals) as an antioxidant,
Granulation was performed to obtain a composition pellet (B). Using a three-layer blown film molding machine, a three-layer film with a film thickness of 100 μm (intermediate layer 66 μm, front and back coating layers 17 μm each) so that the composition pellet (A) becomes the intermediate layer and the composition pellet (B) becomes the coating layer. I got

Examples 2 to 6 A multilayer film was obtained in the same manner as in Example 1 except that the compound (1), the compound (2) and the compounding weight ratio shown in Table 1 were used.

Examples 7 and 8 A multilayer film was obtained in the same manner as in Example 1 except that the polyolefin resins shown in Table 1 were used.

(Comparative Examples 1 and 2) A multilayer film was obtained in the same manner as in Example 1 except that the compounding weight ratios shown in Table 1 were used.

Comparative Example 3 A multilayer film was obtained in the same manner as in Example 1 except that Compound (2) was not used.

Comparative Example 4 A multilayer film was obtained in the same manner as in Example 1 except that Compound (1) was not used.

Comparative Example 5 A multilayer film was obtained in the same manner as in Example 1, except that the amounts shown in Table 1 (the amount of the mixture in the intermediate layer) were used.

Table 1 shows the results of evaluating the physical properties of these film samples.

From the results of the above Examples and Comparative Examples, in the Comparative Examples in which the compounding weight ratio and compounding amount of the compound (1) and the compound (2) were out of the scope of the claims of the present invention, respectively, It can be seen that the physical properties of either the transparency or the heat retention required as the properties of the film are inferior, whereas the physical properties of the examples according to the present invention are excellent overall.

[0039]

[Table 1]

[0040]

[Table 2]

Remarks (A): [Al ₂ (Li _0.94 Mg _0.06 ) (OH) ₆ ] ₂ (Si ₂ O ₅ ) _1.06
0.35H ₂ O (B): [Al ₂ (Li _0.90 Mg _0.10 ) (OH) ₆ ] ₂ (Si ₃ O ₇ ) _1.10
3.0H ₂ O (C): [Al ₂ (Li _0.90 Zn _0.20 ) (OH) ₆ ] ₂ (Si ₃ O ₇ ) _1.25 ·
1.5H ₂ O Synthetic hydrotalcite: Mg _0.69 Al _0.31 (OH) ₂ (CO ₃ )
_0.15・ 0.54H ₂ O Natural hydrotalcite: Mg _0.75 Al _0.25 (OH) ₂ (CO ₃ )
_0.125 · 0.5H ₂ O EVA: ethylene-vinyl acetate copolymer (vinyl acetate content of 5 wt%, MFR2g / 10 min) EVA: ethylene-vinyl acetate copolymer (vinyl acetate content of 15 wt%, MFR2g / 10 MinPE) MePE: Ethylene / α-olefin copolymer produced with a metallocene catalyst (MFR: 2 g / 10 min, density 0.9)
07) Kernel “KF270” manufactured by Nippon Polychem PE: Branched polyethylene produced by a high-pressure radical method catalyst (MFR: 0.7 g / 10 min, density 0.92)
4) Novatec LD "LF240" made by Nippon Polychem

[0042]

The agricultural polyolefin film of the present invention is excellent in transparency and heat retention, and is extremely useful.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Keiko Iwase F-term (reference) 2B024 DB01 DB07 2B029 EB03 EB16 EC02 EC09 EC18 RA03 4F100 AA17H AC10H AK03A AK03B AK03C AK62A AK62B AK62C AK68 AL05B AL05C BA03 BA06 BA10B BA10C EH20 EH202 GB01 JJ02 JN01

Claims (2)

[Claims] 1. The compounding weight ratio of lithium / aluminum / magnesium and / or zinc composite hydroxide condensed silicate and a hydrotalcite compound is 30/70 to 70 /.
An agricultural multilayer film having a polyolefin-based resin composition layer containing 8 to 20% by weight of a composition in the range of 30 as an intermediate layer and having a polyolefin-based resin composition coating layer on both surfaces thereof. And the composition is 5 to 1
An agricultural polyolefin resin multilayer film characterized by containing 5% by weight. 2. The agricultural polyolefin resin multilayer film according to claim 1, wherein at least one layer of the polyolefin resin used for the multilayer film is an ethylene / α-olefin copolymer obtained by copolymerization with a metallocene catalyst. .